KR102191638B1 - Double-sided pressure-sensitive adhesive sheet - Google Patents

Abstract

A double-sided adhesive sheet 1 used for bonding between the first hard body 4 and the second hard body 5, wherein the double-sided adhesive sheet 1 is adhered to the first hard body 4 1 Adhesion surface (11S) and a second adhesive surface (12S) adhered to the second rigid body (5) is provided, and a loop tack test of the first adhesive surface (11S) to the first rigid body (4) When the peel force by L1 and the peel force by the roof tack test of the second adhesive surface 12S to the second hard body 5 is L2, the ratio of L1 to L2 (L1/L2) is 0.0005 The double-sided pressure-sensitive adhesive sheet (1) of -0.05 and having a contact angle of at least 85° or more with respect to diiodomethane in the first adhesive surface 11S. This double-sided adhesive sheet 1 is excellent in rework property, and when peeling the first hard body 4 and the second hard body 5 bonded using the double-sided adhesive sheet 1, at least the first hard body It can be peeled so that the sieve 4 can be reused.

Description

Double-sided adhesive sheet {DOUBLE-SIDED PRESSURE-SENSITIVE ADHESIVE SHEET}

The present invention relates to a double-sided adhesive sheet used for bonding between a plurality of hard bodies.

BACKGROUND ART Various mobile electronic devices such as mobile phones and tablet terminals in recent years have a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like.

In the above-described display, a polarizing film or the like is attached to a display module using a double-sided adhesive sheet, but at the time of this bonding, a shift may occur in the bonding position. Here, since the display module is expensive, it is usually reused. Therefore, the adhesive sheet as described above is required to have a rework property that can be peeled off from the display module so that the display module can be reused. Therefore, Patent Documents 1 and 2 propose a double-sided pressure-sensitive adhesive sheet having rework property.

Japanese Patent Laid-Open No. 2004-231723 Japanese Patent Application Publication No. 2013-32483

In recent years, the display is often a touch panel type, in which case a touch panel including a glass plate or a plastic plate is installed on the surface side of the display module. Even when attaching these display module and touch panels, the use of double-sided adhesive sheets is increasing, but bonding of hard materials (hard bodies) to each other with double-sided adhesive sheets as described above is a matter of bonding between films or films. It is more difficult than bonding the hard body, and the yield at the time of bonding is liable to decrease.

Therefore, in the above case, the need for peeling the two hard bodies so that the display module can be reused is higher, but it is very difficult to peel the two hard bodies bonded by the double-sided adhesive sheet. In the pressure-sensitive adhesive sheet disclosed in Patent Document 1, only the rework property in the case of peeling off the films or the film and the hard body is considered, and it is difficult to peel the two hard bodies. Further, the pressure-sensitive adhesive sheet disclosed in Patent Document 2 considers the case of peeling off two hard bodies, but its rework property is not sufficient.

The present invention is a double-sided adhesive sheet used for bonding between a first hard body and a second hard body to be used for reuse, which has been made in view of the above facts, and is a first hard bonded adhesive layer It is an object of the present invention to provide a double-sided pressure-sensitive adhesive sheet having excellent rework properties that can be peeled off so that the first hard body can be reused when the sieve and the second hard body are separated.

In order to achieve the above object, the first aspect of the present invention is a double-sided adhesive sheet used for adhesion between a first hard body and a second hard body, wherein the double-sided adhesive sheet comprises the first hard body or the double-sided A first adhesive surface adhered to a member on the side of the first hard body than the adhesive sheet, and a second adhesive surface adhered to a member on the side of the second hard body than the second hard body or the double-sided adhesive sheet, , The peeling force of the first adhesive surface with respect to the member located on the side of the first hard body than the first hard body or the double-sided adhesive sheet by a roof tack test specified in JIS Z0237:2009 is L1, and the second hard When the peeling force of the second adhesive surface to the member on the side of the second hard body than the sieve or the double-sided adhesive sheet by a roof tack test specified in JIS Z0237:2009 is L2, the L1 relative to the L2 A double-sided pressure-sensitive adhesive sheet, wherein the ratio (L1/L2) of is 0.0005 to 0.05, and a contact angle of at least the first adhesive surface with respect to diiodomethane is 85° or more (Invention 1).

The double-sided pressure-sensitive adhesive sheet according to the above invention (invention 1) is excellent in reworkability with respect to at least the first hard body by specifying the peel force ratio and the contact angle to diiodomethane by the loop tack test as described above. Therefore, when peeling the 1st hard body and the 2nd hard body bonded using the said double-sided adhesive sheet, it can peel so that the 1st hard body can be reused at least.

In the above invention (invention 1), a laminate obtained by adhering the first hard body and the second hard body with the double-sided pressure-sensitive adhesive sheet is provided with the first hard body and the first adhesive in the double-sided pressure-sensitive adhesive sheet. As the peeling force at the time of peeling at the interface of the surface, according to JIS Z0237:2009, the peeling force measured under conditions of a peeling rate of 300 mm/min and a peeling angle of 90° is preferably 1 to 40 N/25 mm. (Invention 2).

In the above invention (inventions 1 and 2), it is preferable that the double-sided adhesive sheet includes a first adhesive layer having the first adhesive surface and a second adhesive layer having the second adhesive surface (invention 3).

In the above invention (invention 3), it is preferable that a core material is provided between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer (invention 4).

In the above invention (Invention 3 and 4), it is preferable that the second pressure-sensitive adhesive layer is composed of an acrylic pressure-sensitive adhesive containing a (meth)acrylic acid ester polymer (Invention 5).

In the above invention (invention 5), the weight average molecular weight of the (meth)acrylic acid ester polymer is 200,000 to 1 million, and the thickness of the second pressure-sensitive adhesive layer is preferably 10 to 400 μm (invention 6).

In the above invention (invention 6), it is preferable that the second pressure-sensitive adhesive layer has a level difference following rate of 20% or more (invention 7).

In the above inventions (inventions 3 to 7), it is preferable that the first pressure-sensitive adhesive layer is made of a silicone pressure-sensitive adhesive containing organopolysiloxane (invention 8).

In the above invention (invention 8), it is preferable that the silicone pressure-sensitive adhesive contains an addition-type organopolysiloxane and an organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit (invention 9).

In the above invention (invention 4 to 9), it is preferable that the core material is made of a polyester film (invention 10).

In the above inventions (Inventions 1 to 10), it is preferable that the first hard body is a display module (Invention 11).

In the above inventions (Inventions 1 to 11), it is preferable that the second hard body is a cover material (Invention 12).

In the above inventions (inventions 1 to 12), it is preferable that the first hard body and the second hard body are members constituting a touch panel (invention 13).

The double-sided adhesive sheet according to the present invention is excellent in rework property, and when peeling the first and second hard bodies bonded together using the double-sided adhesive sheet, at least the first hard body can be peeled off so that reuse is possible. have.

1 is a cross-sectional view of a double-sided adhesive sheet according to an embodiment of the present invention.
Fig. 2 is a cross-sectional view of a laminate obtained by bonding a first hard body and a second hard body together using a double-sided adhesive sheet.
Fig. 3 is a plan view of a laminate produced by bonding a first hard body and a second hard body together with a double-sided pressure-sensitive adhesive sheet in Examples and Comparative Examples.

Hereinafter, an embodiment of the present invention will be described.

As shown in FIG. 1, the double-sided adhesive sheet 1 according to the present embodiment is sandwiched between the two release sheets 2a and 2b so as to contact the release surfaces of the two release sheets 2a and 2b. A laminate comprising the release sheet 2a, the double-sided adhesive sheet 1 and the release sheet 2b is hereinafter referred to as the double-sided adhesive sheet 3 with a release sheet.

In the present embodiment, the release sheets 2a and 2b are not essential constituent elements, and are peeled and removed when the double-sided pressure-sensitive adhesive sheet 1 is used. In addition, the peeling surface of a release sheet in this specification refers to the surface which has peelability in a peeling sheet, and includes both a peeling-treated surface and a surface exhibiting peelability even if no peeling treatment has been performed.

The double-sided adhesive sheet 1 according to the present embodiment is, as shown in FIG. 2, on a laminate 10 formed by laminating a first hard body 4 and a second hard body 5 provided for reuse. In this case, it is used for adhesion between the first hard body 4 and the second hard body 5. This double-sided adhesive sheet 1 may be directly adhered to the first hard body 4 and/or the second hard body 5, and a member laminated on the side of the first hard body 4 and/or the second hard body It may be adhered to the member laminated on the side of the sieve 5. That is, in FIG. 2, the double-sided pressure-sensitive adhesive sheet 1 is directly adhered to the first hard body 4 and the second hard body 5 to directly bond both, but is not limited thereto.

In addition, the "hard body" in this specification means that the Young's modulus measured in conformity with JIS K7127:1999 is 10 GPa or more. The rigid body may be composed of a single layer or a single member, or may be composed of a plurality of layers or a plurality of members. In the latter case, it is a single water composed of a plurality of layers or a plurality of members, and if the Young's modulus is satisfied, the water can be said to be a hard body even if some of the layers or members do not satisfy the Young's modulus.

As shown in FIG. 2, the double-sided adhesive sheet 1 according to the present embodiment is a first hard body 4 than the double-sided adhesive sheet 1 in the first hard body 4 or the laminate 10 obtained. The first adhesive surface 11S adhered to the member on the) side (hereinafter sometimes referred to as the ``first hard body side member''), and the two sides in the second hard body 5 or the obtained laminate 10 It is provided with a 2nd adhesive surface 12S adhere|attached to the member which is on the 2nd hard body 5 side than the adhesive sheet 1 (it may be referred to as a "second hard body side member" hereafter).

In the double-sided adhesive sheet 1 of the present embodiment, peeling force of the first adhesive surface 11S against the first hard body 4 or the first hard body side member (for example, a glass plate) by a roof tack test L1, when the peeling force of the second adhesive surface 12S against the second hard body 5 or the second hard body side member (for example, a glass plate) by a roof tack test is L2, L1 against L2 The ratio (L1/L2) of is 0.0005 to 0.05, preferably 0.001 to 0.03, and particularly preferably 0.002 to 0.02. Here, the loop tack test is a test specified in JIS Z0237:2009, and in detail, it is as shown in the test example mentioned later.

In addition, in the double-sided adhesive sheet 1 of the present embodiment, the contact angle with respect to diiodomethane in at least the first adhesive surface 11S is 85° or more, preferably 88 to 99°, and particularly preferably Is 90-95°. The contact angle of the adhesive surface with respect to diiodomethane in the present specification is the static contact angle immediately after the diiodomethane contacts the adhesive surface, and a value measured at 23°C and 50% RH using a commercially available contact angle measuring device. To do. Specifically, it is as shown in the test example mentioned later.

Since the ratio of L1 to L2 is within the above range, and the contact angle with respect to diiodomethane on at least the first adhesive surface 11S is within the above range, the first hard body bonded using the double-sided adhesive sheet 1 When peeling (4) and the second hard body 5, at the interface between the first adhesive surface 11S of the double-sided adhesive sheet 1 and the first hard body 4 or the first hard body side member, double-sided adhesion The sheet 1 and the first hard body 4 or the first hard body side member are well separated so that the first hard body 4 or the second hard body 5 is broken, or the first hard body 4 Alternatively, there is no residual adhesive on the first hard body side member. Thereby, at least the first hard body 4 can be reused. As described above, the double-sided pressure-sensitive adhesive sheet 1 in which the ratio of L1 to L2 and the contact angle to diiodomethane are within the above ranges has excellent rework properties.

If the ratio of L1 to L2 is less than 0.0005, the adhesive force on the first adhesive surface 11S becomes too small, and in use of the laminate 10, etc., the first adhesive surface 11S and the first hard body ( 4) Or, unintentional peeling occurs at the interface of the first hard body side member. On the other hand, when the ratio of L1 to L2 exceeds 0.05, when peeling the first hard body 4 and the second hard body 5, the second hard body 5 is broken or the first hard body 4 ) Or, the adhesive remains in the member on the first hard body side, and cannot be peeled off so that the first hard body can be reused.

In addition, if the contact angle of the first adhesive surface 11S with respect to diiodomethane is less than 85°, the wettability of the first adhesive surface 11S increases, and the adherend (the first hard body 4 or the first hard body The adhesion to the body-side member) becomes high, the above-described peeling cannot be performed satisfactorily, and the rework property is inferior.

Moreover, in the double-sided adhesive sheet 1 of this embodiment, the contact angle with respect to diiodomethane in the 2nd adhesive surface 12S may also be 85 degrees or more. Thereby, the occurrence of residual adhesive to the adherend (the second hard body 5 or the second hard body-side member) of the second adhesive surface 12S is suppressed, and the second hard body 5 can be reused. It becomes possible to do.

When the double-sided adhesive sheet 1 is configured such that the ratio of L1 to L2 is within the above range and the contact angle to diiodomethane is within the above range, the first adhesive surface 11S and the second adhesive surface 12S are configured. It may be made of a single layer, may be made of a plurality of layers, or may be made of a plurality of materials whose interlayers are not clear. From the viewpoint of ease of manufacture, the double-sided adhesive sheet 1 includes a first adhesive layer 11 having a first adhesive surface 11S and a second adhesive surface 12S, as shown in FIGS. 1 and 2. It is preferable to have the 2nd adhesive layer 12 which has it. Moreover, from the viewpoint of the handling property of the double-sided adhesive sheet 1, it is particularly preferable that the core material 13 is provided between the first adhesive layer 11 and the second adhesive layer 12. In addition, the 1st adhesive surface 11S is the surface opposite to the 2nd adhesive layer 12 in the 1st adhesive layer 11, The 2nd adhesive surface 12S is the 2nd adhesive layer 12 It is the surface opposite to the 1st adhesive layer 11 in ).

In addition, in the test examples described later, a glass plate was used as the hard body as an adherend, and the peeling force was measured and the rework property was evaluated, but the same evaluation result was obtained even when other materials were used as the hard body as the adherend. I think.

1. Double-sided adhesive sheet

(1) first adhesive layer

The first pressure-sensitive adhesive layer 11 may be composed of a pressure-sensitive adhesive in which the first pressure-sensitive adhesive surface 11S satisfies the peel force ratio (L1/L2) and the contact angle for diiodomethane, but specifically organopolysiloxane, especially additive type It is preferably composed of a silicone pressure-sensitive adhesive containing organopolysiloxane (cured product of). Such a silicone pressure-sensitive adhesive is easy to satisfy the above physical properties.

The addition-type organopolysiloxane is preferably obtained by reacting an organopolysiloxane having an alkenyl group and an organohydrogenpolysiloxane having a siloxane bond as a main skeleton.

The organopolysiloxane having a siloxane bond as a main skeleton and an alkenyl group is a compound represented by the following average unit formula (1), and is preferably a compound having at least two alkenyl groups in the molecule.

R ¹ _a SiO _(4-a)/2 ···(1)

(Wherein, R ¹ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8, which is identical to or different from each other, and a is 1.5 to 2.8, preferably 1.8 to 2.5. , More preferably an integer in the range of 1.95 to 2.05)

Examples of the unsubstituted or substituted monovalent hydrocarbon group bonded to the silicon atom represented by R ¹ include vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, cyclohexenyl group, octenyl group Alkenyl group, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, etc. Alkyl groups such as, phenyl group, tolyl group, xylyl group, aryl group such as naphthyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, and some or all of the hydrogen atoms of these groups are fluorine, bromine, chlorine What substituted with halogen atom, such as a cyano group, etc., For example, a chloromethyl group, a chloropropyl group, a bromoethyl group, a trifluoropropyl group, a cyanoethyl group, etc. are mentioned. As the alkenyl group, a vinyl group is preferable from the viewpoint of short curing time and productivity.

Organohydrogenpolysiloxane has a SiH group in its molecule. When the alkenyl group of the organopolysiloxane reacts with the SiH group of the organohydrogenpolysiloxane, both are subjected to an addition reaction to obtain an addition-type organopolysiloxane.

Since the addition-type organopolysiloxane cures satisfactorily in the presence of a platinum catalyst, the silicone pressure-sensitive adhesive preferably contains a platinum catalyst. Examples of the platinum catalyst include platinum black, chloroplatinum, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and olefins, and platinum bisacetoacetate.

The content of the platinum catalyst in the silicone pressure-sensitive adhesive is preferably 0.01 to 3 parts by mass, and particularly preferably 0.05 to 2 parts by mass, based on 100 parts by mass of the addition-type organopolysiloxane. When the content of the platinum catalyst is within the above range, the addition-type organopolysiloxane can be cured to form the first pressure-sensitive adhesive layer 11 without interfering with coating.

In the addition-type organopolysiloxane, an organopolysiloxane (silicone resin) containing a trifunctional or tetrafunctional siloxane unit in a molecule can be contained in order to increase adhesive strength within a range that does not impair the object of the present invention.

The content of the organopolysiloxane containing trifunctional or tetrafunctional siloxane units in the silicone pressure-sensitive adhesive is preferably 1 to 100 parts by mass, particularly 5 to 80 parts by mass, based on 100 parts by mass of the addition type organopolysiloxane. It is preferable, and further, it is preferable that it is 10-50 mass parts. When the content of the organopolysiloxane containing trifunctional or tetrafunctional siloxane units is 100 parts by mass or less, the contact angle of the first adhesive surface 11S to diiodomethane is likely to be 85° or more, and excellent reworkability This is easy to obtain.

The thickness of the first pressure-sensitive adhesive layer 11 is preferably 5 to 50 µm, particularly preferably 10 to 40 µm, and further preferably 15 to 35 µm. When the thickness of the 1st adhesive layer 11 is 5 micrometers or more, a desired adhesive force can be exhibited. In addition, when the thickness of the first pressure-sensitive adhesive layer 11 is 50 μm or less, mixing of residual solvents or air bubbles resulting from the manufacturing process is effectively prevented, and stability of adhesive force and optical properties can be excellent.

To form the first pressure-sensitive adhesive layer 11, for example, an addition-type organopolysiloxane, an organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit as desired, and a platinum catalyst, methyl ethyl ketone, toluene, A coating solution diluted to about 10 to 60% by mass with a solvent such as ethyl acetate or xylene may be applied to an application object (for example, the core material 13), followed by heating to cure. The heating temperature is preferably about 90 to 180°C, and the heating time is preferably about 1 to 5 minutes.

Here, the peeling force L1 by the roof tack test of the first adhesive surface 11S with respect to the first hard body 4 or the first hard body side member (for example, a glass plate) is 0.005 to 1 N/25 mm It is preferably in the range of, particularly preferably 0.01 to 0.5 N/25 mm, and further preferably 0.02 to 0.3 N/25 mm. When the peeling force is 0.005N/25mm or more, it is possible to prevent unintended peeling at the interface between the first adhesive surface 11S and the first hard body 4 when using the laminate 10, etc. I can. Moreover, when the said peeling force is 1N/25 mm or less, peelability of the 1st adhesive layer 11 with respect to an adherend is maintained satisfactorily, and excellent rework property is exhibited.

In addition, a laminate formed by adhering the hard body 5 (for example, a glass plate) of the first hard body 4 (for example, a glass plate) 302 with a double-sided adhesive sheet 1, The peeling force when peeling at the interface between the sieve 4 and the first adhesive surface 11S is preferably 1 to 40 N/25 mm, particularly preferably 5 to 35 N/25 mm, and further 10 to It is preferably 30N/25mm. If the peeling force is 40 N/25 mm or less, the laminate including the second hard body 5 and the double-sided adhesive sheet 1 can be easily peeled off from the first hard body 4, and thus excellent Workability is exhibited. In addition, when the peeling force is 1 N/25 mm or more, it is possible to prevent unintended peeling at the interface between the first adhesive surface 11S and the first hard body 4 when using the laminate 10 or the like. can do. In addition, the said peeling force is a peeling force measured under the conditions of a peeling speed of 300 mm/min and a peeling angle of 90 degrees according to JIS Z0237:2009, and a specific measuring method is a test example (evaluation of rework property) mentioned later. As shown.

(2) 2nd adhesive layer

The second pressure-sensitive adhesive layer 12 may be made of an adhesive in which the second adhesive surface 12S satisfies the above-described peel force ratio (L1/L2), but is specifically made of an acrylic adhesive containing a (meth)acrylic acid ester polymer. It is desirable to be configured. Such an adhesive is easy to satisfy the above physical properties.

The acrylic pressure-sensitive adhesive contains a (meth)acrylic acid ester polymer (a), and preferably contains the (meth)acrylic acid ester polymer (a) crosslinked with a crosslinking agent (b). In addition, in this specification, (meth)acrylic acid ester means both acrylic acid ester and methacrylic acid ester. Other similar terms are the same. In addition, the concept of "copolymer" is also included in "polymer". Moreover, it is preferable that the (meth)acrylic acid ester polymer (a) does not have an ultraviolet curable group from the viewpoint of facilitating adjustment of the adhesive force.

It is preferable that the (meth)acrylic acid ester polymer (a) contains an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer constituting the polymer. Thereby, the obtained adhesive can express preferable adhesiveness. In addition, the (meth)acrylic acid ester polymer (a) includes a (meth)acrylate alkyl ester having 1 to 20 carbon atoms in the alkyl group, a monomer having a functional group reacting with the crosslinking agent (b) (reactive functional group-containing monomer), as desired. It is particularly preferred that it is a copolymer of other monomers used accordingly.

Examples of the alkyl (meth)acrylate ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and n (meth)acrylate. -Pentyl, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myrisyl (meth)acrylate , Palmityl (meth)acrylate, stearyl (meth)acrylate, and the like. Among them, from the viewpoint of further improving the adhesiveness, (meth)acrylate esters having 1 to 8 carbon atoms in the alkyl group are preferable, and methyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate This is particularly preferred. In addition, these may be used individually or may be used in combination of 2 or more types.

The (meth)acrylic acid ester polymer (a) preferably contains 40 to 99% by mass of an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer, and particularly 70 to 98 It is preferable to contain it by mass%, and it is preferable to contain 80-95 mass% further.

As the reactive functional group-containing monomer, a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), etc. are preferably mentioned. These may be used alone or in combination of two or more.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and (meth)acrylate. )(Meth)acrylate hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate. Among them, from the viewpoint of reactivity of the hydroxyl group in the obtained (meth)acrylic acid ester polymer (a) with the crosslinking agent (b) and copolymerization with other monomers, 2-hydroxyethyl (meth)acrylate and 4-hydroxyethyl (meth)acrylic acid. Hydroxybutyl is preferred. These may be used alone or in combination of two or more.

As a carboxyl group-containing monomer, ethylenically unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid, are mentioned, for example. Among them, acrylic acid is preferable from the viewpoint of reactivity of the carboxyl group in the obtained (meth)acrylic acid ester polymer (a) with the crosslinking agent (b) and copolymerization with other monomers. These may be used alone or in combination of two or more.

As an amino group-containing monomer, aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. are mentioned, for example. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (a), as a monomer unit constituting the polymer, preferably contains 1 to 40% by mass of a reactive functional group-containing monomer, particularly preferably 2 to 30% by mass, and furthermore It is preferable to contain 5-20 mass %.

Examples of the other monomers include (meth)acrylate alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, and (meth)acrylate esters having an aliphatic ring such as cyclohexyl (meth)acrylate. , Acrylamide, non-crosslinkable acrylamide such as methacrylamide, (meth)acrylic acid N,N-dimethylaminoethyl, (meth)acrylic acid N,N-dimethylaminopropyl, etc. ) Acrylic acid ester, vinyl acetate, styrene, and the like. These may be used alone or in combination of two or more.

The polymerization aspect of the (meth)acrylic acid ester polymer (a) may be a random copolymer or a block copolymer.

The weight average molecular weight of the (meth)acrylic acid ester polymer (a) is preferably 200,000 to 1 million, particularly preferably 300,000 to 900,000, and further preferably 400,000 to 700,000. In addition, the weight average molecular weight in this specification is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

When the weight average molecular weight of the (meth)acrylic acid ester polymer (a) is 200,000 or more, the cohesive force of the second adhesive layer 12 becomes high, and the double-sided adhesive sheet 1 from the adherend on the second adhesive surface 12S Even when it is peeled off, the adhesive residue is less likely to occur on the adherend. On the other hand, in capacitive touch panels, etc., in many cases, a printed layer that becomes a stepped portion is formed at the periphery of the cover material to hide the wiring layer, but if the weight average molecular weight of the (meth)acrylic acid ester polymer (a) is 1 million or less , The second pressure-sensitive adhesive layer 12 has good followability (step followability) with respect to the print step. That is, when the second pressure-sensitive adhesive layer 12 and the cover material having the step are bonded together, since the second pressure-sensitive adhesive layer 12 follows the step, there are no lifts or bubbles in the vicinity of the step. Moreover, even if these laminates are placed under durable conditions, generation of air bubbles, peeling, etc. in the vicinity of the step is suppressed.

Moreover, in the said acrylic adhesive, (meth)acrylic acid ester polymer (a) may be used individually by 1 type, and may be used in combination of 2 or more types.

As the crosslinking agent (b), any one that reacts with the reactive functional group possessed by the (meth)acrylic acid ester polymer (a) may be used. For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, an amine crosslinking agent, a melamine crosslinking agent, an aziridine crosslinking agent, and a hydrazine type A crosslinking agent, an aldehyde type crosslinking agent, an oxazoline type crosslinking agent, a metal alkoxide type crosslinking agent, a metal chelate type crosslinking agent, a metal salt type crosslinking agent, an ammonium salt type crosslinking agent, and the like. Among the above, when the reactive functional group of the (meth)acrylic acid ester polymer (a) is a hydroxyl group, it is preferable to use an isocyanate crosslinking agent having excellent reactivity with a hydroxyl group, and the reactive functional group possessed by the (meth)acrylic acid ester polymer (a) When is a carboxyl group, it is preferable to use an epoxy-based crosslinking agent or a metal chelate-based crosslinking agent excellent in reactivity with a carboxyl group. Further, the crosslinking agent (b) may be used alone or in combination of two or more.

The isocyanate crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate. Adducts that are reactants with low-molecular active hydrogen-containing compounds such as alicyclic polyisocyanates such as, and their biuret body, isocyanurate body, and further ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. Sieves and the like. Among them, from the viewpoint of reactivity with a hydroxyl group, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferred.

As an epoxy crosslinking agent, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, etc. are mentioned.

The metal chelate crosslinking agent contains at least a metal chelate compound. Examples of the metal chelate compound include metal chelate compounds such as aluminum, zirconium, titanium, zinc, iron, and tin with metal valence, but aluminum chelate compounds and zirconium chelate compounds are preferable from the viewpoint of performance, and aluminum chelate compounds are particularly preferable. Moreover, it is preferable that these metal chelate compounds are an acetylacetone complex.

The amount of crosslinking agent (b) used is preferably 0.001 to 10 parts by mass, particularly preferably 0.01 to 5 parts by mass, and further preferably 0.05 to 1 parts by mass based on 100 parts by mass of the (meth)acrylic acid ester polymer (a). Do. By making the crosslinking agent (b) 0.001 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (a), peeling (rework) between the first hard body 4 and the first pressure-sensitive adhesive layer 11 can be performed. In this case, it is possible to prevent unintentionally peeling between the second hard body 5 and the second adhesive layer 12. Moreover, by making the crosslinking agent (b) into 10 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (a), it is possible to ensure the level difference followability of the second adhesive layer 12.

When the adhesive composition containing the (meth)acrylic acid ester polymer (a) containing a reactive functional group-containing monomer and the crosslinking agent (b) as a monomer unit constituting the polymer is heated, the crosslinking agent (b) is a (meth)acrylic acid ester It reacts with the reactive functional group of the reactive functional group-containing monomer constituting the polymer (a). Thereby, a structure in which the (meth)acrylic acid ester polymer (a) is crosslinked by the crosslinking agent (b) is formed, and the cohesive strength of the obtained pressure-sensitive adhesive layer, and furthermore, strength and durability are improved.

To the acrylic pressure-sensitive adhesive, various additives commonly used as desired, for example, a refractive index adjuster, an antistatic agent, a tackifier, a silane coupling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, and the like may be added.

The thickness of the second pressure-sensitive adhesive layer 12 is preferably 10 to 400 µm, particularly preferably 20 to 300 µm, and further preferably 50 to 250 µm. When the thickness of the second pressure-sensitive adhesive layer 12 is 10 μm or more, good step-following property is exhibited, and when the thickness of the second pressure-sensitive adhesive layer 12 is 400 μm or less, the workability is improved. Further, the second pressure-sensitive adhesive layer 12 may be formed as a single layer, or may be formed by stacking multiple layers.

When the second pressure-sensitive adhesive layer 12 is composed of an acrylic pressure-sensitive adhesive To form the second pressure-sensitive adhesive layer 12, a coating solution containing an acrylic pressure-sensitive adhesive and a solvent as desired is applied to the target (for example, the release sheet 2b). It is applied to the peeling surface) and heat-treated to form a coating film. When the curing period is not necessary, the formed coating film becomes the second pressure-sensitive adhesive layer 12 as it is, and when the curing period is required, it becomes the second pressure-sensitive adhesive layer 12 after the curing period has elapsed.

The heat treatment can also serve as a drying treatment when volatilizing a diluted solvent or the like of the coating solution. When performing heat treatment, the heating temperature is preferably 50 to 150°C, and particularly preferably 70 to 120°C. In addition, the heating time is preferably 30 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be set at room temperature (eg, 23° C., 50% RH).

When the acrylic pressure-sensitive adhesive contains a (meth)acrylic acid ester polymer (a) having a reactive functional group and a crosslinking agent (b), the (meth)acrylic acid ester polymer (a) is formed by the crosslinking agent (b) by the heat treatment. A crosslinked structure is formed.

Here, the peeling force L2 by the roof tack test of the second adhesive surface 12S with respect to the second hard body 5 or the second hard body side member (for example, a glass plate) is 1 to 70 N/25 mm It is preferably 3 to 50 N/25 mm, and more preferably 5 to 45 N/25 mm. If the peeling force is 1N/25mm or more, it is possible to prevent unintended peeling at the interface between the second adhesive surface 12S and the second hard body 5 when using the laminate 10 or the like. have. On the other hand, when the peeling force exceeds 70 N/25 mm, when the second hard body 5 also wants to be reused, there is a case where the adhesive remains on the side of the second hard body 5 and cannot be reused.

It is preferable that it is 20% or more, and, as for the level difference following rate of the 2nd adhesive layer 12, it is preferable that it is especially 25-80%, and it is further preferable that it is 30-70%. When the second pressure-sensitive adhesive layer 12 has a level difference following rate of 20% or more, when the second pressure-sensitive adhesive layer 12 and a cover material such as a touch panel having a level difference due to the printing layer are bonded together, the second pressure-sensitive adhesive layer 12 ) Satisfactorily follows the step, so there are no lifts or bubbles in the vicinity of the step. Moreover, even if these laminates are placed under durable conditions, generation of air bubbles, peeling, etc. in the vicinity of the step is suppressed.

In addition, the level difference following rate is represented by the following formula, and a specific measurement method is as shown in the test example mentioned later.

Step tracking rate (%)={(height of step filled without gaps or bubbles)/(thickness of adhesive layer)}×100

(3) heartwood

The core material 13 imparts rigidity to the double-sided adhesive sheet 1 to improve the handling properties of the double-sided adhesive sheet 1. It is preferable that this core material 13 is comprised from a plastic film. Examples of plastic films include polyester films made of polyester such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, and cellulose films such as triacetylcellulose. , Polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, and plastic film such as cycloolefin resin film ; And laminates of two or more of these. The plastic film may be uniaxially stretched or biaxially stretched. Among these, a polyester film is preferable, and a polyethylene terephthalate film is particularly preferable.

In the core material 13 made of the plastic film as described above, for the purpose of improving adhesion with the adjacent first adhesive layer 11 and/or the second adhesive layer 12, one-sided or both-sided as desired. For example, surface treatment or primer treatment by an oxidation method or the like can be performed. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromium oxidation treatment (wet), flame treatment, hot air treatment, ozone, and ultraviolet irradiation treatment. These surface treatment methods are appropriately selected depending on the type of the plastic film, but in general, the corona discharge treatment method is preferably used from the viewpoint of effect and operability.

The thickness of the core material 13 is preferably 2 to 250 µm, particularly preferably 5 to 125 µm, and further preferably 10 to 75 µm, from the viewpoint of improving the handling properties of the double-sided adhesive sheet 1 Do.

2. Release sheet

The release sheet 2a, 2b is not particularly limited, and a known plastic film can be used. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate Film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluororesin Film or the like is used. Moreover, these crosslinked films are also used. Moreover, these laminated films may be sufficient.

It is preferable that the peeling surface (especially the surface in contact with the double-sided adhesive sheet 1) of the peeling sheets 2a and 2b is subjected to a peeling treatment (however, when the adhesive layer 11 is a silicone adhesive, peeling treatment It is also preferable to use a plastic film that has not been applied as it is). Examples of the release agent used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. In addition, it is preferable to use one of the release sheets 2a and 2b as a medium-release type release sheet having a high peeling force, and the other release sheet as a light release type release sheet having a small peeling force.

The thickness of the release sheets 2a and 2b is not particularly limited, but is usually about 20 to 150 µm.

3. Preparation of double-sided adhesive sheet with release sheet attached

As an example of manufacture of the double-sided pressure-sensitive adhesive sheet 3 with the release sheet attached, after forming the first pressure-sensitive adhesive layer 11 on one side of the core material 13, on the exposed side of the pressure-sensitive adhesive layer 11, a release sheet ( 2a) is laminated so that the peeling surface is in contact, and this is referred to as a first laminate. On the other hand, the 2nd pressure-sensitive adhesive layer 12 is formed on the peeling surface of the peeling sheet 2b, and this is made into a 2nd laminated body. Subsequently, the first laminate and the second laminate are bonded to each other so that the core material 13 of the first laminate and the second adhesive layer 12 of the second laminate overlap, and the double-sided adhesive sheet 3 with a release sheet attached thereto. ).

4. Use of double-sided adhesive sheet

The laminated body 10 shown in FIG. 2 is obtained by bonding the first hard body 4 and the second hard body 5 provided for reuse using the double-sided adhesive sheet 1. That is, the laminated body 10 is comprised of the 1st hard body 4, the 2nd hard body 5, and the double-sided adhesive sheet 1 interposed between them.

The double-sided adhesive sheet 1 in this embodiment is provided with the first adhesive layer 11, the core material 13, and the second adhesive layer 12, and the agent in the first adhesive layer 11 1 adhesive surface 11S is adhered to the first hard body 4, and the second adhesive surface 12S in the second adhesive layer 12 is adhered to the second hard body 5 .

As the first hard body 4 provided for reuse, an expensive member, specifically, a display body module, a solar cell module, and the like can be mentioned. As a display module, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, electronic paper, etc. are mentioned, for example. Further, on the side of the double-sided adhesive sheet 1 of this display module, various functional layers (transparent conductive films, etc.) may be formed.

The material of the portion in contact with the double-sided pressure-sensitive adhesive sheet 1 in the above member is usually a glass plate, a plastic plate, a metal plate, a semiconductor plate, and the like, and preferably a glass plate.

Moreover, as the 2nd hard body 5, a glass plate, a plastic plate, a metal plate, a semiconductor plate, or their laminated body etc. are mentioned, for example, Preferably it is a glass plate.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, and the like. I can. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate, or a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, and preferably 0.4 to 3 mm.

In addition, various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be formed on one or both surfaces of the glass plate or plastic plate, or metal wiring may be formed, and an optical member May be laminated. In addition, as the "member on the side of the first hard body than the double-sided adhesive sheet" and the "member on the side of the second hard body than the double-sided adhesive sheet" in the present embodiment, various functional layers and optical members described above are preferably mentioned. I can.

As said optical member, for example, a polarizing plate (polarizing film), a polarizer, a retardation plate (phase difference film), a viewing angle compensation film, a brightness improving film, a contrast improving film, a liquid crystal polymer film, a diffusion film, a hard coat film, a semi-transmissive reflective film And the like.

In order to manufacture the laminate 10, as an example, first, one release sheet 2b of the double-sided adhesive sheet 3 to which the release sheet is attached is peeled off, and the exposed second adhesive layer 12 and the second hard body (5) is attached. Next, the other release sheet 2a is peeled from the double-sided adhesive sheet 3 with the release sheet attached, and the exposed first adhesive layer 11 and the first hard body 4 are bonded.

In the laminated body 10 produced as described above, when a shift occurs at the bonding position, it is necessary to peel the first hard body 4 and the second hard body 5. When the 1st hard body 4 and the 2nd hard body 5 are peeled in this laminated body 10, the 1st adhesive surface 11S of the double-sided adhesive sheet 1 (the 1st adhesive layer 11) At the interface between the first hard body 4 and the double-sided adhesive sheet 1 (the first adhesive layer 11) and the first hard body 4 are well separated, the first hard body 4 or the first hard body 4 2 The hard body 5 does not break or the adhesive remains in the first hard body 4. Thereby, at least the first hard body 4 can be reused. Thus, the double-sided pressure-sensitive adhesive sheet 1 according to the present embodiment is very excellent in rework property.

It is preferable that the laminated body 10 in this embodiment is a touch panel, especially a capacitive touch panel, and therefore, the 1st hard body 4 and the 2nd hard body 5 comprise a touch panel. It is preferable that it is absent. In this case, the first hard body 4 is preferably a display module or a member including a display module, and the second hard body 5 is a cover material made of a glass plate or a plastic plate, or a member including a cover material. It is preferable to be. The second hard body 5 may be a cover material having a sensor function (a circuit of a transparent conductive film is formed on the cover material) or a cover material integrated sensor (OGS: One Glass Solution).

A printed layer serving as a step may be formed at the periphery of the cover member on the side of the double-sided adhesive sheet 1. The second pressure-sensitive adhesive layer 12 in which the weight average molecular weight of the (meth)acrylic acid ester polymer (a) constituting the second pressure-sensitive adhesive layer 12 and the thickness of the second pressure-sensitive adhesive layer 12 are defined as described above, The level difference followability with respect to the level difference by the printing layer becomes good.

The material constituting the printing layer is not particularly limited, and a known material for printing is used. The thickness of the print layer, that is, the height of the step, is preferably 3 to 45 µm, more preferably 5 to 35 µm, particularly preferably 7 to 25 µm, and still more preferably 7 to 15 µm.

In addition, the thickness of the printing layer (the height of the step) is preferably 2 to 40% of the thickness of the second pressure-sensitive adhesive layer 12, particularly preferably 5 to 30%, and further 10 to 20%. desirable. Thereby, the 2nd adhesive layer 12 is easy to follow a step|step difference by a printing layer, and it is suppressed that lift, air bubbles, etc. generate|occur|produce near a step|step difference.

In addition, although not shown in FIG. 2, between the double-sided adhesive sheet 1 and the first hard body 4 and/or the double-sided adhesive sheet 1 and the second hard body 5 in the laminate 10 In between, one layer or multiple layers of the film sensor for a touch panel may be formed. Moreover, a desired pressure-sensitive adhesive layer may be formed between the film sensors of a plurality of layers. The film sensor is made of, for example, a base film and a transparent conductive film made of patterned tin-doped indium oxide (ITO).

Embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents falling within the technical scope of the present invention.

For example, any one of the release sheets 2a and 2b in the double-sided pressure-sensitive adhesive sheet 3 with a release sheet may be omitted. Moreover, another member may exist between the double-sided adhesive sheet 1 and the 1st hard body in the laminated body 10, and/or between the double-sided adhesive sheet 1 and the 2nd hard body.

Example

Hereinafter, the present invention will be described more specifically by examples and the like, but the scope of the present invention is not limited to these examples.

[Production Example 1]

Additive type organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KS-847H) 100 parts by mass (solid content conversion value; the same below) consisting of organopolysiloxane and organohydrogenpolysiloxane having a siloxane bond as the main skeleton and having a vinyl group. And, 20 parts by mass of organopolysiloxane (silicone resin; manufactured by Toray Dow Corning, brand name: SD-4584) containing trifunctional or tetrafunctional siloxane units, and 20 parts by mass of platinum catalyst (manufactured by Toray Dow Corning, brand name: SRX-212 ) 1.5 parts by mass was mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a pressure-sensitive adhesive coating liquid.

Apply the obtained pressure-sensitive adhesive coating liquid to the side of the easily adhesive layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo, PET A4300, thickness: 38 μm) having an easily adhesive layer as a core material so that the thickness after drying is 35 μm. After coating with a knife coater, heat treatment was performed at 120° C. for 2 minutes to form a pressure-sensitive adhesive layer (silicon pressure-sensitive adhesive layer A) made of a silicone adhesive. Thereafter, the adhesive surface of the silicone pressure-sensitive adhesive layer A was protected with an untreated PET film (manufactured by Toray Corporation, T60, thickness: 50 µm) to which no peeling treatment or easy-adhesion treatment was applied as a release sheet.

[Production Example 2]

Additive type organopolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., brand name: KS-847H) 100 parts by mass and trifunctional or tetrafunctional consisting of organopolysiloxane and organohydrogenpolysiloxane having a siloxane bond as the main skeleton and having a vinyl group 50 parts by mass of organopolysiloxane (silicone resin; manufactured by Toray Dow Corning, brand name: SD-4584) and 1.5 parts by mass of platinum catalyst (manufactured by Toray Dow Corning, brand name: SRX-212) are mixed and sufficiently The mixture was stirred and diluted with methyl ethyl ketone to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating liquid was applied to one side of a polyethylene terephthalate film (manufactured by Toyobo, PET A4300, thickness: 38 μm) as a core material with a knife coater so that the thickness after drying became 35 μm, and then 2 at 120° C. It heat-processed for a minute, and the adhesive layer (silicone adhesive layer B) which consists of a silicone adhesive was formed. Thereafter, the adhesive surface of the silicone pressure-sensitive adhesive layer B was protected with an untreated PET film (manufactured by Toray Corporation, T60, thickness: 50 µm) to which no peeling treatment or easy-adhesion treatment was applied as a release sheet.

[Production Example 3]

90 parts by mass of n-butyl acrylate (BA) and 10 parts by mass of acrylic acid (AA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was a weight average molecular weight of 500,000.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., TERAD-C) as an epoxy crosslinking agent ) 0.05 parts by mass was mixed, stirred sufficiently, and diluted with ethyl acetate to obtain a pressure-sensitive adhesive coating liquid.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent, so that the thickness after drying was 25 μm. After coating with a knife coater, heat treatment was performed at 90° C. for 1 minute to form a pressure-sensitive adhesive layer made of acrylic pressure-sensitive adhesive. Similarly, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the peeling-treated surface of the release sheet, overlapped with the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer (acrylic pressure-sensitive adhesive layer A) having a thickness of 50 μm was formed on the peeling-treated surface of the release sheet. did.

[Production Example 4]

The pressure-sensitive adhesive coating solution obtained in Production Example 3 was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) obtained by peeling off one side of a polyethylene terephthalate film with a silicone-based release agent, and the thickness after drying was 25 After coating with a knife coater so that it might become mu m, it heat-processed at 90 degreeC for 1 minute, and the adhesive layer which consists of an acrylic adhesive was formed. In the same way, five pieces of those having a 25 µm-thick adhesive layer formed on the peeling-treated surface of the release sheet were produced. And each adhesive layer was superimposed, and the 150 micrometers-thick adhesive layer (acrylic adhesive layer A') was formed on the peeling-treated surface of a release sheet.

[Production Example 5]

70 parts by mass of 2-ethylhexyl acrylate (2EHA), 10 parts by mass of methyl methacrylate (MMA) and 20 parts by mass of 2-hydroxyethyl acrylate (HEA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was 600,000 in weight average molecular weight.

100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 0.2 parts by mass of trimethylolpropane-modified tolylene diisocyanate (TDI; manufactured by Soken Chemical Co., Ltd., L-45) as an isocyanate-based crosslinking agent were mixed, sufficiently stirred, and ethyl acetate By diluting with, an adhesive coating liquid was obtained.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent, so that the thickness after drying was 25 μm. After coating with a knife coater, heat treatment was performed at 90° C. for 1 minute to form a pressure-sensitive adhesive layer made of acrylic pressure-sensitive adhesive. Similarly, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the peeling-treated surface of the release sheet, overlapped with the pressure-sensitive adhesive layer, and a pressure-sensitive adhesive layer (acrylic pressure-sensitive adhesive layer B) having a thickness of 50 μm was formed on the peeling-treated surface of the release sheet. did.

[Production Example 6]

75 parts by mass of n-butyl acrylate (BA), 20 parts by mass of ethyl acrylate (EA), and 5 parts by mass of acrylic acid (AA) were copolymerized to prepare a (meth)acrylic acid ester polymer. When the molecular weight of this (meth)acrylic acid ester polymer was measured by the method described later, it was a weight average molecular weight of 900,000.

By mixing 100 parts by mass of the (meth)acrylic acid ester polymer obtained in the above step and 1.0 parts by mass of aluminum acetylacetonate (manufactured by Soken Chemical Co., Ltd., M-5A) as a metal chelate-based crosslinking agent, sufficiently stirred and diluted with ethyl acetate, A pressure-sensitive adhesive coating liquid was obtained.

The obtained pressure-sensitive adhesive coating liquid was applied to the peeling-treated surface of a release sheet (manufactured by Lintec, SP-PET3811, thickness: 38 μm) in which one side of a polyethylene terephthalate film was peeled off with a silicone-based release agent, so that the thickness after drying was 25 μm. After coating with a knife coater, heat treatment was performed at 90° C. for 1 minute to form a pressure-sensitive adhesive layer made of acrylic pressure-sensitive adhesive. Similarly, a pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the peeling-treated surface of the release sheet, overlapped with the pressure-sensitive adhesive layer, and an adhesive layer having a thickness of 50 μm (acrylic pressure-sensitive adhesive layer C) was formed on the peeling-treated surface of the release sheet. did.

Table 1 shows the composition of the pressure-sensitive adhesive (subject) prepared in each preparation example, the weight average molecular weight (Mw) of the (meth)acrylic acid ester polymer, the type and amount of the crosslinking agent, and the thickness of the pressure-sensitive adhesive layer.

Here, the above-described weight average molecular weight (Mw) is a weight average molecular weight in terms of polystyrene measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).

<Measurement conditions>

GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL(×2)

TSK gel G2000HXL

Measurement solvent: tetrahydrofuran

·Measurement temperature: 40℃

[Example 1]

As the first pressure-sensitive adhesive layer, on the surface of the PET film (core material) side of the laminate made of the PET film (core material)/silicone pressure-sensitive adhesive layer A/untreated PET film (release sheet) obtained in Production Example 1, as a second pressure-sensitive adhesive layer, The acrylic pressure-sensitive adhesive layer A formed in Production Example 3 was affixed. The obtained laminate was cut into a width of 25 mm x a length of 200 mm, and a release sheet/acrylic adhesive layer A (second adhesive layer)/PET film (core)/silicone adhesive layer A (first adhesive layer)/untreated PET film A double-sided pressure-sensitive adhesive sheet with a release sheet made of (release sheet) was obtained.

The release sheet on the side of the first pressure-sensitive adhesive layer was peeled from the double-sided pressure-sensitive adhesive sheet to which the obtained release sheet was attached, and the exposed silicone pressure-sensitive adhesive layer A was a soda lime glass having a size of 105 mm×140 mm (manufactured by Central Glass Co., Ltd., Thickness: 1.1 mm, Young's modulus: 71 GPa; The double-sided pressure-sensitive adhesive sheet was affixed to the first rigid body so as to contact the reference numeral 4) in FIG. 3 and so that the double-sided pressure-sensitive adhesive sheet protrudes in the longitudinal direction (see FIG. 3). .

Subsequently, the release sheet on the side of the second pressure-sensitive adhesive layer is peeled from the double-sided pressure-sensitive adhesive sheet, and for the exposed acrylic pressure-sensitive adhesive layer A, soda lime glass (manufactured by Central Glass Co., Ltd., having a size of 35 mm×70 mm) 1.1 mm, Young's modulus: 71 GPa; symbol 5) in FIG. 3 was bonded together. At this time, the second hard body was bonded to the double-sided pressure-sensitive adhesive sheet so that the end portion in the length direction of the double-sided adhesive sheet on the first hard body and the end portion in the length direction of the second hard body were at the same position (Fig. 3). In this way, soda lime glass (second hard body)/acrylic adhesive layer A (second adhesive layer)/PET film (core material)/silicone adhesive layer A (first adhesive layer)/soda lime glass (first hard body) ) To obtain a laminate.

In addition, in the present embodiment, from the viewpoint of ease of adjusting the adhesive position by hand, the silicone adhesive layer A was first affixed to the first hard body, but when industrial production is considered, the second hard body and the acrylic adhesive layer A were first applied. After bonding, the silicone pressure-sensitive adhesive layer A and the first hard body may be bonded thereafter.

[Examples 2 to 5, Comparative Examples 1 to 2]

As shown in Table 2, except for changing the materials of the first adhesive layer and the second adhesive layer, in the same manner as in Example 1, the second hard body / the second adhesive layer / the core material / the first adhesive layer / the first hard A laminate made of a sieve was produced. However, in Comparative Examples 1 and 2, by attaching the laminate of the acrylic pressure-sensitive adhesive layer/release sheet obtained in Production Example on both surfaces of the PET film (manufactured by Toyobo, PET A4300; thickness 38 μm) serving as the core material, the release sheet/ Acryl adhesive layer B or C/PET film (core material) / acrylic adhesive layer A / obtaining a double-sided adhesive sheet with a release sheet consisting of a peeling sheet, and using the double-sided adhesive sheet, a second hard body/second adhesive layer A laminate made of /core material/first adhesive layer/first hard body was produced.

[Test Example 1] (Loop Tack Test)

The peeling force of the roof tack on the surface (the surface of the side opposite to the core material side) of each pressure-sensitive adhesive layer produced in Production Examples 1 to 6 was measured as follows. The pressure-sensitive adhesive layers of Production Examples 1 and 2 were cut into a tape shape having a width of 25 mm, a length of 300 mm, and a gap of 25 mm at both ends, and then the untreated PET film was removed. On the other hand, for the pressure-sensitive adhesive layers of Production Examples 3 to 6, the exposed side of the pressure-sensitive adhesive layer was bonded to a polyethylene terephthalate (PET) film (manufactured by Toyobo, PET A4300, thickness: 38 μm), and cut in the same manner as above, After that, the release sheet was removed.

Subsequently, the surface of the pressure-sensitive adhesive layer was made outward, the ends were aligned to form a loop, and the gaps at both ends were attached to the upper grip (head part) of the tensile tester. On the other hand, soda-lime glass, which is an adherend, was mounted horizontally on the lower grip of the tensile tester. Subsequently, the test piece was brought into contact with the adherend (soda lime glass) until the distance from the head portion became 60 mm, and 15 seconds later, the adherend was lowered to 300 mm/min, and the peel strength at that time was measured. The average value was taken as the peeling force of the roof tack (N/25 mm).

Further, based on the above results, the ratio (L1/L2) of the peel force (L1) of the first adhesive layer to the peel force (L2) of the second adhesive layer used in the Examples and Comparative Examples was calculated. The results are shown in Table 2.

[Test Example 2] (Measurement of diiodomethane contact angle)

The contact angle (°) of the surface of each pressure-sensitive adhesive layer prepared in Production Examples 1 to 6 (the surface opposite to the core material side) was measured according to JIS R3257 using a contact angle meter (manufactured by Kyowa Kaimen Chemical Co., Ltd., DM-701). It measured by the quasi-solution static method. As a droplet, diiodomethane was used. The results are shown in Table 2.

[Test Example 3] (Evaluation of rework property)

The double-sided pressure-sensitive adhesive sheet protruding from the laminate produced in Examples and Comparative Examples was set in a universal tensile tester (manufactured by Orientech, Tensilon UTM-4-100), and according to JIS Z0237:2009, a peel rate of 300 The peeling force (N/25 mm) of the first pressure-sensitive adhesive layer in the double-sided pressure-sensitive adhesive sheet with respect to the first hard body was measured under the conditions of mm/min and a peel angle of 90° (peeling upward). The results are shown in Table 2.

Moreover, after performing the said peeling test, the presence or absence of adhesive residue on the surface of the 1st hard body was visually confirmed, and the adhesive residue was evaluated based on the following criteria. The results are shown in Table 2.

◎… There was no residual adhesive.

○… There was an adhesive residual of less than 20% of the bonding area.

△... There was an adhesive residue of 20% or more and less than 50% of the bonding area.

×… There was 50% or more of the adhesive residual of the bonding area.

[Test Example 4] (Evaluation of step followability)

(a) Preparation of sample for evaluation

UV-curable ink (manufactured by Teikoku Ink, product name "POS-911 Black") on the surface of a glass plate (manufactured by NSG Flash Transfer, product name "Corning Glass Eagle XG", 90 mm long × 50 mm wide × 0.5 mm thick) Screen printing was performed in a frame shape (outer shape: 90 mm long x 50 mm wide, 5 mm wide) so that the coating thickness became any one of 5 µm, 10 µm, 15 µm, and 20 µm. Subsequently, ultraviolet rays are irradiated (80 W/cm 2, metal halide lamp 2 lamps, lamp height 15 cm, belt speed 10 to 15 m/min), the printed ultraviolet curing ink is cured, and the step by printing (step difference Height: a glass plate having a stepped height of 5 µm, 10 µm, 15 µm, and 20 µm) was prepared.

Each pressure-sensitive adhesive layer (pressure-sensitive adhesive layer on a peeling sheet) prepared in Production Example was bonded to an easily-adhesive layer of a polyethylene terephthalate film (manufactured by Toyobo, PET A4300, thickness: 100 μm) having an easily-adhesive layer. Next, the release sheet was peeled off, and the pressure-sensitive adhesive layer was exposed. Then, using a laminator (manufactured by Fuji Plaza, product name "LPD3214"), the laminate was laminated on a glass plate having each step so that the pressure-sensitive adhesive layer covers the entire frame-shaped printing surface, and this was used as a sample for evaluation.

(b) Evaluation of the sample for evaluation

The obtained sample for evaluation was subjected to an autoclave treatment for 30 minutes under the conditions of 50°C and 0.5 MPa, and then allowed to stand at normal pressure, 23°C and 50% RH for 24 hours. Subsequently, it was stored for 72 hours under a moist heat condition of 85°C and 85%RH, and then the level difference followability was evaluated. The level difference followability is judged by whether or not the printing level difference is completely filled by the pressure-sensitive adhesive layer, and when a gap or air bubbles or the like is observed at the interface between the printing level difference and the pressure-sensitive adhesive layer, it is judged that the printing level difference cannot be followed. Here, the level difference followability was evaluated by the level difference tracking rate (%) based on the following formula. The results are shown in Table 2.

Step tracking rate (%)={(height of print step filled without gaps or bubbles (µm))/(thickness of adhesive layer: 50µm)}×100

As can be seen from Table 2, the double-sided pressure-sensitive adhesive sheet obtained in Examples was excellent in rework property in the case of peeling off the hard body. Moreover, the 2nd adhesive layer of this double-sided adhesive sheet was excellent in level difference followability.

Industrial availability

The double-sided pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding a member including a display module or a display module and a cover material or a member including a cover material in, for example, a capacitive touch panel. .

1: double-sided adhesive sheet
11: first adhesive layer
11S: 1st adhesive surface
12: second adhesive layer
12S: 2nd adhesive surface
13: heartwood
2a, 2b: release sheet
3: Double-sided adhesive sheet with a release sheet attached
4: first hard body
5: second hard body
10: laminate

Claims (14)

As a double-sided adhesive sheet used for bonding between a first hard body and a second hard body,
The double-sided adhesive sheet includes a first adhesive surface bonded to the first hard body or a member laminated to the first hard body, and a second bonded to the second hard body or a member laminated to the second hard body It has an adhesive surface,
The peeling force of the first adhesive surface with respect to the first hard body or the member laminated on the first hard body by the roof tack test specified in JIS Z0237:2009 is L1, the second hard body or the second The ratio of the L1 to the L2 (L1/L2) when the peeling force of the second adhesive surface with respect to the member laminated on the rigid body by the roof tack test specified in JIS Z0237:2009 is L2, 0.0005 to 0.05, and at least a contact angle with respect to diiodomethane on the first adhesive surface is 85° or more. The multilayer body according to claim 1, wherein the first hard body and the second hard body are bonded to each other with the double-sided adhesive sheet, and an interface between the first hard body and the first adhesive surface in the double-sided adhesive sheet. As the peeling force at the time of peeling at, according to JIS Z0237:2009, the peeling force measured under conditions of a peeling rate of 300 mm/min and a peeling angle of 90° is 1 to 40 N/25 mm. Sheet. The double-sided adhesive sheet according to claim 1, wherein the double-sided adhesive sheet comprises a first adhesive layer having the first adhesive surface and a second adhesive layer having the second adhesive surface. The double-sided pressure-sensitive adhesive sheet according to claim 3, wherein a core material is provided between the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer. The double-sided pressure-sensitive adhesive sheet according to claim 3, wherein the second pressure-sensitive adhesive layer is made of an acrylic pressure-sensitive adhesive containing a (meth)acrylic acid ester polymer. The double-sided pressure-sensitive adhesive sheet according to claim 5, wherein the weight average molecular weight of the (meth)acrylic acid ester polymer is 200,000 to 1 million, and the thickness of the second pressure-sensitive adhesive layer is 10 to 400 µm. The double-sided pressure-sensitive adhesive sheet according to claim 6, wherein the second pressure-sensitive adhesive layer has a level difference following rate of 20% or more. The double-sided pressure-sensitive adhesive sheet according to claim 3, wherein the first pressure-sensitive adhesive layer is made of a silicone pressure-sensitive adhesive containing organopolysiloxane. The double-sided pressure-sensitive adhesive sheet according to claim 8, wherein the silicone pressure-sensitive adhesive contains an addition-type organopolysiloxane and an organopolysiloxane containing a trifunctional or tetrafunctional siloxane unit. The double-sided adhesive sheet according to claim 4, wherein the core material is made of a polyester film. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the first hard body is a display module. The double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the second hard body is a cover material. The double-sided adhesive sheet according to claim 1, wherein the first hard body and the second hard body are members constituting a touch panel. With the first hard body,
With a second hard body,
The double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 13, which is interposed between the first hard body and the second hard body, bonds the first hard body and the second hard body together. Laminate.

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